Most evangelicals find this to be just another silly Catholic belief that can be quickly dismissed by anyone with a basic knowledge of the Scriptures, seeing as the Bible mentions that Jesus had brothers and sisters.
One such example is Matthew 12.46: "While he was still speaking to the people, behold, his mother and his brothers stood outside, asking to speak to him." Other examples include Matthew 13.55, Mark 6.3 (this is the one that mentions sisters), John 2.12, John 7.3, John 7.5, John 7.10, Acts 1.14, 1 Corinthians 9.5, and Galatians 1.19.
Here's a traditional response:
"The word brothers, we have formerly mentioned, is employed, agreeably to the Hebrew idiom, to denote any relatives whatever; and, accordingly, Helvidius displayed excessive ignorance in concluding that Mary must have had many sons, because Christ’s brothers are sometimes mentioned."There is another passage usually brought up as a evidence that Mary was not perpetually a virgin, Matthew 1.24-25: "When Joseph woke from sleep, he did as the angel of the Lord commanded him: he took his wife, but knew her not until she had given birth to a son. And he called his name Jesus."
To say that Joseph "knew her not until she had given birth to a son", many evangelicals argue, seems to imply very strongly that Joseph did "know" Mary after she had given birth to Jesus. Another traditional response:
"This passage afforded the pretext for great disturbances, which were introduced into the Church, at a former period, by Helvidius. The inference he drew from it was, that Mary remained a virgin no longer than till her first birth, and that afterwards she had other children by her husband. Jerome, on the other hand, earnestly and copiously defended Mary’s perpetual virginity. Let us rest satisfied with this, that no just and well-grounded inference can be drawn from these words of the Evangelist, as to what took place after the birth of Christ.
He is called first-born; but it is for the sole purpose of informing us that he was born of a virgin. It is said that Joseph knew her not till she had brought forth her first-born son: but this is limited to that very time. What took place afterwards, the historian does not inform us. Such is well known to have been the practice of the inspired writers."
The explanations quoted above in defense of the perpetual virginity of Mary, while accurate, are fairly poignant (and at times even a bit harsh). So who are they from?
None other than the great Protestant Reformer John Calvin.
The first quote is from from his Commentary on Matthew, Mark, Luke, Vol 2, Matthew 13.53-58 and Mark 6.1-6, and the second is from his Commentary on Matthew, Mark, Luke, Vol 1, Matthew 1.18-25.
For full disclosure, Calvin seems to indicate in a sentence following the second quote that, while he doesn't think there is Scriptural warrant for denying the perpetual virginity of Mary, he doesn't think the question is of much importance either:
"Certainly, no man will ever raise a question on this subject, except from curiosity; and no man will obstinately keep up the argument, except from an extreme fondness for disputation."But notice that Calvin thought that "Helvidius displayed excessive ignorance in concluding that Mary must have had many sons, because Christ’s brothers are sometimes mentioned," (my emphasis) - the very same conclusion that many evangelicals today make from those passages.
And regarding the other common evangelical argument from Matthew 1.24-25, Calvin thought "that no just and well-grounded inference can be drawn from these words of the Evangelist, as to what took place after the birth of Christ" and that "[w]hat took place afterwards, the historian does not inform us. Such is well known to have been the practice of the inspired writers."
Calvin was not alone among the Reformers in defending the perpetual virginity of our Blessed Mother.
"When Matthew says that Joseph did not know Mary carnally until she had brought forth her son, it does not follow that he knew her subsequently; on the contrary, it means that he never did know her . . . This babble . . . is without justification . . . he has neither noticed nor paid any attention to either Scripture or the common idiom." (That Jesus was Born a Jew)
"Christ, our Savior, was the real and natural fruit of Mary's virginal womb . . . This was without the cooperation of a man, and she remained a virgin after that. [...] Christ . . . was the only Son of Mary, and the Virgin Mary bore no children besides Him . . . I am inclined to agree with those who declare that 'brothers' really mean 'cousins' here, for Holy Writ and the Jews always call cousins brothers." (Sermons on John)Huldrych Zwingli wrote:
"I firmly believe that Mary, according to the words of the gospel as a pure Virgin brought forth for us the Son of God and in childbirth and after childbirth forever remained a pure, intact Virgin." (Zwingli Opera, Corpus Reformatorum, Berlin, 1905, v. 1, p. 424)Even John Wesley, in 1749, wrote:
"I believe that He [Jesus] was made man, joining the human nature with the divine in one person; being conceived by the singular operation of the Holy Ghost, and born of the blessed Virgin Mary, who, as well after as before she brought Him forth, continued a pure and unspotted virgin." (Letter to a Roman Catholic)Calvin, Luther, Zwingli, and Wesley were simply maintaining the long-standing traditional belief on the matter. Here are just a few witnesses:
St Gregory of Nyssa, On the Holy Generation of Christ, 5 (4th century):
"For if Joseph had taken her to be his wife, for the purpose of having children, why would she have wondered at the announcement of maternity, since she herself would have accepted becoming a mother according to the law of nature?"St Augustine, Sermons 186.1 (early 5th century):
“It was not the visible sun, but its invisible Creator who consecrated this day for us, when the Virgin Mother, fertile of womb and integral in her virginity, brought him forth, made visible for us, by whom, when he was invisible, she too was created. A Virgin conceiving, a Virgin bearing, a Virgin pregnant, a Virgin bringing forth, a Virgin perpetual. Why do you wonder at this, O man?”St Thomas Aquinas, Summa Theologica, III.28.3 (13th century):
"Without any hesitation we must abhor the error of Helvidius, who dared to assert that Christ's Mother, after His Birth, was carnally known by Joseph, and bore other children.
For, in the first place, this is derogatory to Christ's perfection: for as He is in His Godhead the Only-Begotten of the Father, being thus His Son in every respect perfect, so it was becoming that He should be the Only-begotten son of His Mother, as being her perfect offspring.
Secondly, this error is an insult to the Holy Ghost, whose "shrine" was the virginal womb, wherein He had formed the flesh of Christ: wherefore it was unbecoming that it should be desecrated by intercourse with man.
St Thomas Aquinas
Thirdly, this is derogatory to the dignity and holiness of God's Mother: for thus she would seem to be most ungrateful, were she not content with such a Son; and were she, of her own accord, by carnal intercourse to forfeit that virginity which had been miraculously preserved in her.
Fourthly, it would be tantamount to an imputation of extreme presumption in Joseph, to assume that he attempted to violate her whom by the angel's revelation he knew to have conceived by the Holy Ghost.
We must therefore simply assert that the Mother of God, as she was a virgin in conceiving Him and a virgin in giving Him birth, did she remain a virgin ever afterwards."Of course, most Christians today still believe in the perpetual virginity of Mary (think Catholics and Orthodox). The practice of evangelicals today of denying the perpetual virginity of Mary is a fairly recent innovation - a peculiar historical aberration, particularly since evangelicals would consider themselves to be conservative Christians - that can't even find historical precedent among the primary magisterial Reformers; for that, one can only look to a hand-full of 4th century teachers who were otherwise universally rejected as heretics. Catholics, on the other hand, have maintained the 2000 year tradition that our blessed and holy mother Mary was indeed not only a virgin before Jesus' birth but also perpetually a virgin thereafter.